1. Field of the Invention
The present invention relates to a suspension for supporting a magnetic head used in a hard disk drive.
2. Discussion of the Background
A magnetic head suspension needs to have an increased resonance frequency in a torsion mode and a bending mode, in order to accurately position a magnetic head on a target track by moving the magnetic head in a seek direction at a high speed.
Conventionally, it has been proposed to improve the torsion mode and the bending mode by bending the external edge and/or the internal edge of a load beam over the whole region in a longitudinal direction thereby to form a flange, as disclosed in Japanese Examined Patent Publication No. 58-22827 (1983) and U.S. Pat. No. 3,931,641.
However, the magnetic head suspensions described in those cited references are insufficient in the following points.
The magnetic head suspensions described in the patent literature have a flange formed over the whole longitudinal direction of a load beam. With this structure, the torsional rigidity and the bending rigidity of the load beam are improved, but the flange extending the whole longitudinal direction brings about an increase in the mass of the load beam.
This increase in the mass lowers the resonance frequency in the torsion mode and the bending mode of the suspension.
Further, the increase in the mass deteriorates the shock resistance performance of the suspension. In other words, when the mass of the load beam increases, controlling acceleration of the suspension caused by shock is more difficult, which can result in damage to the disk surface due to a backlash of the load beam.